Holistic Review: More internal consistency would have elevated the script, but it's still a fun and timely eco-thriller.

I'm discovering that, when it comes to fiction in general and Doctor Who in particular, I am clearly prejudiced in favor of stories that have straightforward blurbs, an intriguing setting, and a clear, attention-grabbing hook. A description like "In order to escape an alien menace, the Doctor rewrites his biology and memories to become an ordinary human man, teaching at a boys' school in 1913" heightens my anticipation in a way that "Across Peru, Madagascar and Hong Kong, the Doctor and friends face a deadly global threat" does not. The latter blurb suggests that perhaps the story will be rambling instead of focused, or overstuffed instead of giving the plot time to breathe and develop, and that perhaps they're using extremely vague language to cover up for the story's lack of a great hook.

So I'm very happy to report that Praxeus exceeded my expectations. Rather than being overstuffed, unfocused, and/or dull, it actually tells quite an effective story of a mounting worldwide plague, and ties it into environmental concerns that affect the entire planet, no matter whether we're primarily the perpetrators or primarily the victims (because, in the end, we're all the victims of an ecological crisis).

As it turns out, the plot is actually pretty good. To lay out the details, Praxeus involves a race of alien humanoids being wiped out by a bacteria that weaponizes plastics against its host, so in search of a cure, one group of scientists brings the Praxeus bacterium to Earth, with the intention of using the planet as a living petri dish. Though they were planning to infect the planet anyway, they wind up doing an even more thorough job of it than intended when their shuttle crash-lands underneath the Indian Ocean garbage patch, which not only sends astronaut Lang's shuttle spinning off-course, but also releases their entire cargo of Praxeus into the ocean, where it fuses with some of the garbage to create an undersea warren of tunnels. As Praxeus spreads through the plastic in the gyre, swallowing up an American submarine as its seafloor pustule expands, the bacteria also gets scooped up by seabirds who don't realize they're swallowing (virulent) plastic rather than fish. Inside the birds' digestive tract, Praxeus is able to infect them and propagate throughout the bird population once it reaches Peru. From there, using the seabirds as a vector, the infection spreads through scratches and begins killing humans. Meanwhile, the alien researchers have relocated to the west, establishing a lab in Madagascar and a research station (connected to the shuttle by transporter) in Hong Kong. Having abducted astronaut Adam Lang, one team studies him in Hong Kong while Suki works on a cure in Madagascar, until the Doctor turns up. The Doctor discovers that the seabirds' enzymes are attacking Praxeus, and suggests this as the basis for a cure. Suki, revealed to be one of the alien doctors, flees in order to splice together the cure and use it on herself, not realizing that a cure based on Earth biology will accelerate the spread of Praxeus in her own body. Having lost Suki's assistance, the Doctor synthesizes the cure herself, tests it on Adam, and then infuses it into the ship's organic engines before Jake ejects the fuel — and the cure — into the Earth's jetstream, where it spreads across the world and neutralizes Praxeus.

Looking at the big picture, it holds together pretty well, and it's certainly eventful, as the length of the above paragraph will attest. There's definitely not a lot of padding here. But I do have a lot of questions. The truth is, the more you think about the plot, the less it holds together.

My biggest question is this: Praxeus has been presenting as an infection of some kind — a bacterial or viral contagion — from the very first moment we witness its effects, yet the people investigating it hardly take any precautions. We have sick birds covered with unhealthy plumage dropping dead out of the sky, live birds acting as if some controlling influence is affecting their brains and causing them to behave abnormally, and human victims covered in a scaly growth that eventually consumes their entire body and causes them to explode in a shower of dust. That last one is especially problematic, because how do viruses replicate? By using one host to spread themselves to others, just like Praxeus is compelling the birds to scratch people, typically through the expulsion of viral particles. Surely this human powder is chock-full of Praxeus bacteria, yet nobody seems to be the slightest bit worried about breathing in whatever just killed the person who just died. Likewise, Ryan warns Gabriela off touching a dead bird, but he himself reaches right out, with his bare hands, to feel the abnormal plastic shards embedded in a dead woman's face. Later, nobody seems the slightest bit worried about the fact that they're standing in "a world of pure Praxeus", where presumably all of the air is tainted. Ultimately there's no indication that Praxeus is spread through inhalation or touch — only through the bloodstream and by ingestion — but infection through ingestion is way less common than infection by inhalation, and Doctor Who is overflowing with deadly things that kill by touch, so you'd think they would be more careful! In short, the epidemiology is consistent — that's not a problem — but it's weird that 98% of the time, everyone behaves as if they already know how Praxeus is (and isn't) spread, even before they have any idea what the infectious agent is.

Other questions that are never quite answered include:

• If the ship crashes at the bottom of the Indian Ocean, how does Praxeus convert the garbage floating in the upper marine column? (Had some of it settled to the ocean floor?)

• Why does this Praxeus/plastic hybrid create a 'world' with breathable air, rather than simply a solid lump of fused trash? (On a related note, how much breathable air is down there? One assumes a finite amount, and when it's all gone, anyone down there will suffocate.)

• Where has the pollution on the Peruvian riverbank come from? Did the seabirds carry trash back from the gyre, driven to spread Praxeus, or is this purely human garbage that's otherwise unrelated to the episode (and completely coincidental) except for a moral lesson about not littering?

• Assuming I'm correct that the seabird pandemic starts to spread in Peru, why exactly do dozens of infected birds make their way to Madagascar? (Suki outright claims that Praxeus is intelligent, so does it likewise know that she's working on a cure, and sends a flock of birds across the ocean to stop her?)

• Why does Jamila, unlike every other victim, die before the infection consumes and disintegrates her? And why do her eyes cloud over? (I might have theorized that her actual cause of death was by some other means, but see my theory below about Suki's people.)

• I suppose we can assume that Zach is infected when he swallows seawater containing Praxeus, but how does he escape the sub? It's evidently snagged by Praxeus on the bottom of the ocean floor, so he somehow had to evacuate the sub, survive the pressures of the deep ocean until he reached the surface, and then swim over 2,000 miles to reach Madagascar.

• How does Praxeus spread from host to host if it kills each human host within hours of infection? That's not exactly a helpful incubation period for propagation. (Nor do the human hosts seem inclined to scratch other people or... well, anything involving swallowing.)

• Why did Suki and her team set up two different research stations, especially since only the one in Hong Kong is connected by transmat to the ship under the ocean? Wouldn't it make more sense to pool their resources? (Androzani suggests that perhaps Suki thought if she took Adam to the Madagascar lab, Aramu would start to get suspicious. I could buy that.)

• If their ship only crashed a few days ago, at the same time as Lang's shuttle went off-course and the infected seabirds started arriving, how has Suki managed to set up this well-equipped lab in Madagascar, establish her fake credentials, and hire Aramu for long-term assistance? ("One day, I will get here before you" sounds like she's chronically late, not that they've been working together for less than a week.) And why didn't Aramu make a connection between Suki and the sick birds appearing on the seashore at the same time?

• Why did they pick Lang for an experimental subject rather than one or more of the submarine crew? Did he just happen to fall into their clutches, if his escape pod crash-landed near the Indian Ocean gyre? Have they deliberately infected him with Praxeus, or did he swallow seawater too?

• While I greatly appreciate that the Doctor's cure is rooted in actual science, I'm not certain that it makes any sense. Evidently, their idea is to isolate and splice the bird enzyme into an unspecified genetically-engineered virus. Specifically, the Doctor describes this enzyme as, "Two strains from Peru, fighting back, ganging up on the bacteria, holding it back to allow for natural decomposition!"
  • First: if I'm understanding her correctly, the Doctor is implying that the reason the bird enzymes are fighting back against Praxeus is to keep the birds from being taken over long enough that they die and decompose before they can spread the infection? Is that a thing that enzymes would do?
    
  • Second: why does the Doctor say that two strains of bird enzymes from Peru are fighting back? We only see one.
    
  • Third: if the enzymes are merely delaying Praxeus from taking over until the birds are dead, then why do the Doctor and Suki assume that the enzyme DNA will provide a supercharged cure? The birds are still dying; the enzymes aren't saving their lives.
    
  • Sudden theory, after my fourth viewing: is the Doctor saying that the birds, unlike the humans, are not being overwhelmed by Praxeus? That the enzymes are allowing them to decay naturally, rather than to explosively pulverize? That still doesn't explain why most of the humans exploded while they were still alive, but I think it might solve the rest of my confusion. If the enzymes are able to inhibit Praxeus enough to keep it from completely consuming the birds, then I can see how it might make for an effective cure, or at least an effective lifelong treatment regimen.

• Suki says that Praxeus is intelligent, and knows that the Doctor is trying to find a cure to destroy it. But how? (Perhaps that explains why it drives the birds after her?)

• Why does Suki run away the moment the Doctor figures out who she is? I'm sure she expects that Doctor to be furious with her for bringing Praxeus to Earth, but she must surely recognize that the Doctor is, for now, her ally in stopping the virus (and a highly intelligent and capable ally, at that).

• At least we get lip service to the fact that the Doctor plans to bioengineer a virus to destroy the Praxeus bacteria, but man, she whips it up offscreen in record time!

• When did Suki get scratched by the birds? She teleported away before they attacked the lab. (Ahhh wait — they anticipated me on this one! On closer inspection, it turns out that she's wearing long sleeves in the earlier scenes, so the scratch could've happened at any point over the last couple of days. I hereby retract this objection.)

• Suki is a fairly pitiful scientist if she doesn't realize that a cure based on human biology and Earth seabirds might not have quite the same effectiveness on her people. Wouldn't Suki have known to discard the analysis of how Praxeus replicates in humans, and instead base her cure on the data from her own people, which surely must be extensive? (I wondered if perhaps the survivors in the lab ships weren't necessarily trained scientists, but Suki doesn't dispute the Doctor's assumption that they were.)

• Then again, it's also wildly alarming (and extremely irresponsible) that, on the strength of one successful recovery and with no further clinical trials, the Doctor releases her cure-virus worldwide.

• If Suki's people don't disintegrate from Praxeus, why does she? (Is it something to do with the human-based cure that she took? Or is it possible that Praxeus affects them in exactly the same way? We're only assuming that the other two scientists don't go 'poof' because of their alien biology; but Praxeus probably isn't what killed them. The scientist who dies in the undersea base most likely succumbed to his injuries after Jake shot him. So maybe Praxeus can't metastasize in a non-living being? This theory would fit the evidence perfectly if not for Jamila, who also appears to have died before the Praxeus infection overtook her.)

• Praxeus appears to be turning people into plastic, or metastasizing the microplastics through their skin; so how does the cure completely reverse all that cellular damage? Adam surely ought to have massive scars and injuries after he's healed, unless the cure is somehow able to re-convert the plastic back into skin (etc) cells.

• Are we sure that simply dumping a virus onto the surface of the ocean will neutralize the entire Praxeus epidemic? (At the very least, though, presumably it'll inoculate anyone who breathes it in, assuming that the Doctor's engineered virus has sufficient viability when airborne.)

It's kind of a lot, right? To the point that I'm shocked these issues don't sink the episode. But for me, at least, they don't. One critical point, I think, is that most of these issues don't involve what actually happens onscreen, merely the logistics of how those events come to be. It's not that there are lots of massive contradictions, but rather that there's a lot that's never clarified. Undoubtedly, a longer runtime would have given the story breathing room to answer these questions — in 45 minutes, the script only has time to provide the simplest of solutions and the most basic of explanations — but the crucial structure is there. When I can thoroughly enjoy an episode despite a list of plot niggles as long as this, I know that the story has done something right. Or, in this case, a lot of somethings.

While the plot may not be perfect, it's a far better illustration than Orphan 55 of how to tell an effective sci-fi story rooted in contemporary environmental concerns. And it's always been important for Doctor Who to do that — environmental warning tales were a staple of the classic series, from Planet of Giants through the Pertwee era to The Curse of Fenric — because it's much easier to evoke an emotional response in the audience from a story like this, which illustrates the possible consequences of our actions, than simply from reading a news article. (Part of me is worried that the heavy-handed messaging of Orphan 55 will lead people to write off Praxeus as being more preachy than it actually is — the episode's moral is only driven home in one very well-contextualized line — but I have to remind myself that most of those people probably would've written off Praxeus anyway.) For my part, I love that this episode is built around three related problems of plastics in our water supply: birds starving as a result of gorging on plastic that they can't digest, the garbage patches in the oceanic gyres, and microplastics. I'm trying not to let it go to my head that microplastics occurred to me at exactly the same time as they occurred to the Doctor — "It attacks the plastic in the birds, but there's no plastic in humans... Except — ohhh. [...] Microplastics! [...] Alien bacteria homing in on microplastics because humans are full of them!" — and I love that McTighe and Chibnall created an alien menace that kills us by weaponizing particles that we've been unknowingly (or uncaringly) ingesting for decades, along with alien scientists who are taking advantage of our rampant pollution to attempt to find a cure for themselves. Their script turns an omnipresent part of life into a deadly danger, which is a classic technique in sci-fi/horror precisely because it's so effective. I don't know what percentage of the Doctor Who audience was familiar with microplastics before this episode aired, or for that matter with the oceanic trash gyres, so it thrills me that Doctor Who is not only upholding but evolving its original educational remit: it's now being applied to environmental issues as well as science and history, and instead of educating only children, it's at least potentially aimed at educating adults as well. In that sense, the Chibnall era has been a sort of spiritual successor to the Pertwee era, though stories like The Green Death were more focused on issues like pollution and waste-dumping in a general sense (and, as I mentioned with regard to Orphan 55, often allegorically), rather than grounding the plot in specific real-life examples (like The X-Files sometimes did, with its spins on 'ripped-from-the-headlines' concepts). Speaking of which, I'm thrilled that the Doctor considers the Nestene Consciousness as a possibility, because you know lots of us in fandom had the same first thought! (Good thing it wasn't them, because the Nestenes probably could've used microplastics to wipe out all of humanity instantly! Let's hope they never think of that.)

There's another nice, subtle moral lesson in the Doctor's line "Seven billion lives, separate and connected... from the depths of the oceans to the edge of the atmosphere." I'm a sucker for a Playing by Heart style 'everything is interconnected' storyline, so that made me perk up right at the story's start, and though ultimately Praxeus doesn't completely pay off that narrative hint, I still really appreciate the sentiment(s) that the story is espousing. The idea seems to be that we're all responsible for one another; pollution created by one person can affect the lives of many others; and we all need to pitch in to solve this crisis together. It's a great way to send a message that's both uplifting (we're all one connected human race!) and cautionary (we'd better start paying attention to how we're poisoning our planet) at the same time.

Praxeus also deserves praise for being the second story this year that strongly promotes scientific research. Honestly, I'm starting to think that Chibnall is actually asking writers to consider how science can contribute to their plotlines, which is flat-out amazing. I don't think we've seen such consistent attention to scientific detail since the Bidmead era. The Chibnall era hasn't yet indulged in full-on hard-science plotlines of the sort that Bidmead favored, but at this rate, it may be only a matter of time. In this story, the Doctor and Adam wax lyrical about how amazing the life of an astronaut is; the Doctor asks Suki for a wide array of actual scientific equipment, which she uses to investigate and then synthesize a viral cure for Praxeus; Ryan dissects a bird corpse with a scalpel; we learn the meaning of 'pathogen'; Adam and the Doctor geek out over the joys of space travel; and the Doctor self-identifies as a scientist: "Look at us, Suki! Two brilliant scientists. We can fix this!" (Also, when Suki turns out to be a criminal, the Doctor rather cutely growls, "Ohh! I'm a sucker for a scientist!") Even if some of the specifics are invented out of whole cloth, or if the scientific method has to be inaccurately sped up in order to compete with the time-saving nature of the sonic screwdriver, I still far prefer a story that tries to ground its technobabble in actual science, as opposed to a story that jettisons scientific realism altogether and goes whole-hog magic.

As I mentioned at the start, I was initially wary of the fact that Praxeus was set in multiple locations. While it's true that none of these settings makes any particular impact on the plotline — given that they're represented by an unpopulated beach, an unpopulated river, an abandoned building, and an abandoned hospital — it's always a refreshing change to see stories that aren't set in England, and it encourages the deliberate inclusion of a wonderfully multicultural cast, at least in the Peru and Madagascar segments. (Only one character actually appears to be from the country in which these scenes are set, but still.)

Madagascar is portrayed beautifully by South Africa: that beach! those mountains! Thankfully the episode doesn't skimp on showing it off to the fullest, both in daytime and at sunset. And it's not just visual; it also plays a minor plot role, being the spot where Zach makes landfall after escaping the sub.

I was thrilled to finally see Hong Kong as the setting for part of an episode, even though the city doesn't contribute any plot function or indeed any particular atmosphere beyond a few signs and Chinese New Year decorations (which, for some reason, beautify not only the alley but also the interior of a locked, abandoned building). The setting looked sufficiently southeast Asian to please me, but my Hong-Kong-resident cousin Gray was much less satisfied: he was unconvinced by the cobblestoned alley, the like of which he's never seen in Hong Kong, and he objected to the lack of people!

Peru is probably the least effective of the three settings, partly because Gabriela's "most beautiful river in the world" doesn't look like it was all that impressive even before its banks were piled with litter — I was expecting something like Colombia's Caño Cristales! — and partly because the hospital scenes defy belief. If Jamila was only just taken there by ambulance mere hours before, why does the hospital look like it's been completely abandoned for weeks? Why does the hospital's electrical wiring appear to have broken down? How are they allowed to just stroll into the quarantine area? What happened to the doctors who were examining Jamila's body, and for that matter why don't they see a single doctor (or patient) anywhere in the hospital? (Have they all been rapidly infected and consumed by the Praxeus infection that was ravaging Jamila's body? But aside from Jamila, there's no sign of Mr or Ms Big Pile of Dust anywhere.)

Last season, Chibnall came under mild criticism for a perceived lack of LGBTQ+ inclusion. To wit: Angstrom's wife was murdered before The Ghost Monument even started, guard Richard barely had time to mention his boyfriend before he was (allegedly) offed by a Dalek, and Yaz' mother vaguely hinted (with zero followup) that Yaz might be bi. To many viewers, this was a typical string of Bury Your Gays and queerbaiting tropes, which is an absolutely valid concern, though personally I didn't read much into it. Season 11 made fantastic strides in diversity across the board in many other ways, so I didn't feel any particular urgency that every single minority group needed to be represented. However, had that state of affairs continued throughout season 12, it would have become problematic, particularly given that the fan community has been vocal about their desire for greater LGBTQ+ inclusion. And so, in Praxeus, I was delighted to see — though I'd been spoiled on it by a friend in the UK — that ex-policeman Jake Willis and astronaut Adam Lang are married (though separated). Now, there are several ways that this storyline still could've gone south. I was entirely convinced, at different points, that Adam and Jake were doomed. So when the story revealed that Adam's infection had been cured — even though of course it had to happen for the Doctor to save planet Earth — I gasped with delight; and when the Doctor miraculously rescued Jake by materializing the TARDIS around him at the last second, my immense relief (and realization that Jake and Adam were going to get a happy ending) flooded over me in a wave of emotion, and I about lost it. (If only it had been possible for her to rescue Adric the same way!) Likewise, the story could've ended with the two of them deciding that their problems were insurmountable; instead, Jake re-commits to their relationship (er, sort of; more on that later). After half an episode of seeing Jake barely able to muster the enthusiasm even to hold his dying husband's hand, it's an incredibly touching moment when the two of them share a passionate kiss, backlit by the glow of the TARDIS column. "What can I say?" smiles the Doctor, "I'm a romantic." Me too, Doctor!

So this week, season 12 gives us its first Guest Character Who IMHO Would've Made a Great Companion. I see that lots of reviewers online are nominating Gabriela for this title, but my pick is different: Jake Willis (Warren Brown), a Duggan-esque ex-cop with emotional issues. Of course, given that he doesn't even like to travel internationally, he'd probably never join the TARDIS crew, but the character has loads of potential which adds a lot to Praxeus. It's been a while since Doctor Who featured a protagonist who thinks with his fists, and he makes an interesting counterpoint to this especially-pacifistic TARDIS team. Not only does he shoulder-charge and kick in various doors, he shoots down the scientists who are firing at them, which of course the Doctor would not like (and indeed she tosses his gun away the moment she sees it). I also appreciate that neither he nor Adam falls into a single gay stereotype — Jake is a much closer fit to the 'troubled straight cop' archetype, all bullish and aggressive, spoiling for a fight, and drowning his emotions in alcohol — though, having said that, I hope the series is open to including gay characters who are less macho; sometimes the urge to avoid stereotypes can lead to the pendulum swinging a little too far in the opposite direction. As an extra bonus, Jake even gets a nice little character arc. At the start of the story, he's bottling up his emotions and letting out his anger in unhealthy ways. In fact, he's so bad at handling his emotions that when he sees his husband for the first time in nine months, and finds him dying of an alien infection, Jake soon thereafter leaves Adam to cope with the lab tests alone, and goes off to sit on the beach on his own, watching the sunset. By the end, his anger management is still unresolved, but he's beginning to grapple with his emotional distance, and he and Adam have rekindled their relationship. However, I do feel the need to question the way this arc is resolved. Adam asks Jake to "stop dodging life", but what really is going out in a premeditated blaze of glory, if not dodging life? "This is me, not dodging," proclaims Jake, as he unilaterally deserts his husband and his on-hold career in order to bravely sacrifice himself. (Not that I'm complaining, really — it's a heroic character moment, and it demonstrates that Jake can be selfless — but it's not exactly embracing life.) Anyway, he does save the world, twice over (compensating for the autopilot faults by manually flying the ship to the upper atmosphere, and venting the antidote). Great delivery of "Chat chat chat chat chat!", "If he's that impressive, if he's that amazing — which he is — he can't love me the way he says he does," and "Yeah, you guys can go now."

In a dramatic shift from the RTD (and to a lesser degree Moffat) era, this planet-wide crisis is illustrated not through televised news broadcasts, but by actually splitting up the companions on assignment to visit the affected spots in person. Separating the companions to do recon around the world was a brilliant decision, because it gives each of the regulars the chance to carry a plotline on their own. Well, in theory, anyway. It works out better for some than others, but it's a smart move regardless.

For the second week running, Yaz is given the brightest moments to shine, and this week it feels like she really proves her worth as a companion. Finally! She takes control of the investigation in Hong Kong, relying on her intelligence to motivate her actions: she smartly warns Jake off from unhooking Adam until they know why he's attached to the tangle of wires, she deduces that the alien tech is important enough that threatening to destroy it will be a deterrent from violence, and she realizes that the interface panel probably gives them access to loads of valuable intel. Above all, I love that Yaz is determined to go back on her own and fetch the alien tech. Though it's a shame she doesn't do much with it; was studying it for 22 seconds, to find out where it was transmitting, really her only goal? Otherwise, the only thing that really dents her record is the moment when she decides to follow one of the scientists through the transmat. I applaud her bravery and determination, certainly, buuuut does Yaz not consider the fact that the gasmask-wearing villains are wearing gasmasks? That implies that they can't breathe in our atmosphere, and therefore she won't be able to breathe in theirs. (As it turns out, she can, which does rather raise the question: why were they wearing some sort of breathing apparatus?) Gill's performance this week is fantastic. Along with several lines I'll be quoting below, I love that, as Yaz follows the Doctor outside, you can see her thinking about that tech she's left behind.

Happily, this week Graham finally gets to share some one-on-one screentime with Yaz, though the two of them don't really interact with one another. He mostly plays backup to her police officer, which also means that he doesn't accomplish very much in Hong Kong, but he still has a nice little role to play in the plot. I know I said, when I reviewed Nikola Tesla's Night of Terror, that Graham was the Tegan of the group, but this week, he's also the one who most often takes the initiative to compassionately encourage people in distress. Not only does he reassure Adam that he can make it to Suki's lab ("Come on, son! You can do it, a few more steps."), he also takes on the emotional heavy lifting when he goes to comfort Jake on the beach. Granted, his advice isn't anything earth-shattering, but it's nice that he offers a listening ear. It's rare that Graham's experience as a cancer survivor informs his reactions, but this week we have a really great moment where he agrees to guide Jake in setting up an IV for Adam: "I've seen a few intravenous drips in my time. Finally comes in handy!" Walsh gives a great delivery of "Wow, so, you're quite the catch, then.", and "Oh yeah. Clear as mud."

Ryan, meanwhile, handles the Peru plot thread completely solo: meeting Gabriela, playing CDC with the dead bird, and investigating the San Pedro hospital. Back in Madagascar, the Doctor assigns him to dissect a rotting infected seabird, and he barely even flinches. Even though Ryan doesn't really accomplish all that much in the story, it's great to see him taking charge in Peru, and handling the situation basically all on his own.

The thirteenth Doctor appears to have bounced back from the shock of last week, remaining in chipper mode for the entirety of this story. Evidently there's nothing better to cheer up a grumpy Time Lord than an intriguing scientific conundrum and playing matchmaker! For much of the first part of Praxeus, she plays a partly organizational role, pulling the strings behind the scenes while her friends do the legwork, and throughout the story, she does a lot of energetic rushing about. In particular, I love the way the Doctor flits around from place to place as she's needed, especially the moment when she suddenly appears out of nowhere in Hong Kong. Among my favorite of Whittaker's performances this week: the wonder in her voice on "Seven billion lives!", the Doctor's 'I don't have time for this' responses to Jake's bewilderment about the TARDIS interior, and the sinking expression on the Doctor's face when she realizes that the alien scientists did deliberately infect the Earth.

One thing I really appreciate about Praxeus is that, for as much incident as the story packs in, it periodically pauses to spend some quieter time with each of the guest characters, which gives them all some nice development so that we get a sense of their personalities.

Mind you, of the guest characters, Adam Lang (Matthew McNulty) is probably the least developed. We learn from Jake that he's a heroic astronaut, but Adam's dialogue only ever reveals that he is very ill, and that he's in love with Jake. He seems like a lovely, pleasant guy, but I don't feel that we get to know him at all by the end of the story; he merely exists as a counterpoint to Jake's angry, emotionally distant self. But there's a nice moment, as the Doctor is examining him, when she asks what he loved best about being on the ISS.

Gabriela Câmara (Joana Borja) is a fun character, eternally convinced that her travel vlog is so famous that everyone she meets will know who she is. She's like the Brazilian anti-Harriet Jones. Gabriela seems appropriately outgoing and confident for a young woman who travels around the world basically on her own, with just a good friend for company, but she's also not shy about confrontation, which pays narrative dividends when she decides to join forces with Yaz in the hopes of delivering some payback for Jamila's death. I enjoyed Borja's delivery of "I'm guessing you know that", "No, it's not!" (seriously though, who tells someone "hey, it's okay" just after they've discovered that their best friend is dead, and watched her body burst like a puffball?), and her reaction when Suki brandishes a gun.

Her partner in vlogging, Jamila Vélez, is the first human victim of Praxeus, so Gabriela Toloi only has about two scenes playing someone who is alive. This is a great shame, because she's excellent in those two scenes, particularly when wordlessly conveying Jamila's fear about the birds fluttering noisily outside their tent.

Initially, Suki Cheng (Molly Harris) is a lovely role model: yet another talented female biologist, who in this case is studying microfiltration in her exquisitely appointed lab on a scenic Madagascar beach. #lifegoals right? However, the reveal that Suki is actually an alien scientist, who crashlanded on Earth a few days ago in an attempt to find a cure for Praxeus, turns much of what we thought we knew about her on its head. In that light, very little of her backstory makes sense. I've already mentioned the difficulty of believing that Suki could have established her credentials and built this lab in only two days' time, but if she's so concerned that the Doctor has nearly derailed her plans, then why does she summon the Doctor back to Madagascar when the birds start flocking strangely? And if she's only been on Earth for a few days, when has she seen hatchlings regurgitate plastics? (Maybe Suki's just good at coming up with inventive lies on the spot?) Despite these inconsistencies, Harris gives a great performance, making Suki seem intelligent yet approachable, and both grateful for, and just a wee bit resentful of, the Doctor's assistance. Love the annoyed look on Harris' face at "Yes, but only a small supply." and her shifting expression as Suki realizes that taking her hastily-concocted cure might've been a very bad idea.

The one character who is actually native to the country where their scenes are set — presumably, anyway — is Suki's assistant Aramu (Thapelo Maropefela), a thinly characterized but likeable guy. The one true blight on Praxeus is in the way it handles the character. First of all, it's a shame to the point of travesty that he's not given more to do. Presumably he's a scientist too (he mentions that he's "always ready for work, especially work like this"), but we never so much as see him pick up a scientific instrument; from the onscreen evidence, it's equally possible that he's a surfing layabout who just hangs around outside the lab between waves. Given the opportunity to portray a talented Madagascan scientist, a character type that is rarely if ever shown in Western media (which even today has a tendency to portray Africans negatively, primarily as poor and uneducated), why not seize it with both hands? Second, and from a plot standpoint more problematically: why does Aramu stay outside to watch the birds when there's a perfectly good window just inside the lab? That, to me, was a red flag that he was about to bite the... er, sand. Sure enough, Aramu gets attacked by the birds, and after that, oddly we never see him again, so I guess we're meant to presume that he's dead. But can we instead assume that he survived? He must have only been scratched, after all, and the Doctor released the cure into the atmosphere mere minutes after he was infected. Anyway, the fact that Aramu just vanishes from the storyline, and nobody seems to even realize that he's gone, much less care what happened to him, is a tragedy.

As Jake's flash-in-the-pan boss Joyce, Soo Drauet only has a short scene, but I loved her regretful yet firm delivery of "This really isn't working out, is it?" Zach Olsen (Tristan de Beer), the American submarine officer, is another brief role, owing to the fact that he's almost immediately gobbled up by Praxeus, but de Beer conveys Olsen's pain and panic with gut-wrenching believability.

The sets are, I'd say, variable. On the lesser side: Hong Kong and Peru. The Hong Kong research station is appropriately grungy and dilapidated for what appears to be an abandoned warehouse, though as I mentioned earlier, the New Year decorations feel both out of place and on-the-nose. ("You'd never know this building interior was in Hong Kong, so let's scatter around some paper lanterns and dragons that have no cause to be here!") The Peruvian hospital is inappropriately grungy and dilapidated, though it admittedly makes for a more atmospheric set. On the greater side: Madagascar and the ocean. Suki's lab looks convincingly lived-in, with lots of tubing and shelving and some colorful bottles, and interesting equipment that draws the eye. Her ship has an interestingly arrowhead-shaped interior with pleasing recessed lighting. But my favorite is the alien undersea base, which is very clearly designed to look like the inside of a giant trash heap — that was the impression I got of it even before I realized that's exactly what it was — and the walls do faintly echo the shape of the Praxeus rash. And, hey, it's cool that the collapsible TARDIS table, a new (and probably long-needed) element of the console room as of series 12, turns out to boast a little niche with who-knows-what kind of analytic capabilities!

The effects are fantastic, with the high point being the way in which Praxeus overtakes its victims, both Zach and (especially) Jamila, in whom we can even see it bursting through the roof of her mouth. The make-up effect, too, is great, particularly the way Jamila's skin looks red and raw where it borders the Praxeus infection, and the almost petrified look of the alien victim, as if its skin has been encrusted with calcite or kyanite crystals. My second-favorite CGI effect is the gorgeous visual of the glowing fuel-based antidote dispersing through the jetstream. The flock of animated birds is pretty convincing, especially when they swarm the lab like a scene out of Hitchcock, and all of the various shots of spaceships in flight are excellent. Also love the creepy sound effect of the Praxeus plastic-rash consuming its victims, like rodents nibbling on carrots, which often serves as an audible heads-up that someone is taking a turn for the worse. Thumbs-up to the color grading, too, which creates an effective difference in skin tone between the healthy Jake and the dying Adam.

The score this week, though still subtle, does a good job of heightening tension with the use of sustained tones and quiet thrumming, like during the scene of Jamila's death, or Yaz' group exploring the warehouse. I also liked the really cool music as Gabriela and Jamila make their way to the river; but on the downside, the music briefly takes an ill-fitting, oddly jaunty, turn as Gabriela and Yaz walk back into the Hong Kong building.

I've really been looking forward to Jamie Magnus Stone's return as director. Yet again he includes lots of kinetic shots: as Jake chases the teenager, as Jamila is attacked by birds, as the Doctor rushes to Zach's aid, the panning shot of Yaz and Gabriela on the transporter pad, and the literal birds-eye shot as they chase the TARDIS crew. There are also loads of interesting low-angle shots, like the airplane flying over the Hong Kong alley, the Doctor silhouetted against the mountains, Ryan and Gabriela looking at the quarantine sign, and Graham rushing out of the lab to summon the Doctor. This week, my favorite moments were the smash-cut from Adam's pod being buffeted in the atmosphere to the teenager flinging himself through a stack of water bottles, like a War Machine; the shot of Jake tackling him as he reaches the end of an aisle; the freaky shot of dead-Jamila's milky white eyes snapping open; the horrific shots of Jamila's body convulsing, Exorcist-style; the nicely-framed shot of Ryan and Gabriela chilling in the TARDIS doorway, admiring the console room; the masterful reveal of the submarine in front of Gabriela; the Steadicam shot as the Doctor realizes Suki's deception; the dramatic zoom-out to the surface of the Indian Ocean gyre; and the gorgeous effects shot of the TARDIS materializing around Jake. And in terms of visual storytelling, the well-framed moment when the Doctor hustles them away from the ship, and Jake glances back, is — like the similar shot of Yaz, earlier — a nice hint that Jake's about to run back and pilot the ship himself.

Minor points:

• Oh my goodness, we really are in the third decade of the twenty-first century! Help! Time is flying and I do not appreciate it!

• As the birds are dive-bombing toward Jamila, does one of them actually say "Caw!"? (They're surely not crows, right? In which case I guess it would've actually been saying "Kar!"...)

• Not only does Gabriela snore, she is one deep sleeper. Evidently she doesn't wake up when Jamila screams at least three times mere inches away from their tent, nor when Jamila surely attempts to wake her for help after the birds attack (right???), nor when Jamila frantically calls emergency services, nor when the ambulance arrives, nor when the EMTs try to wake her to accompany them to the hospital (right???????). I thought I was a deep sleeper, but she's got me way beat. (To be fair, the plot implies that after the attack, Jamila actually walks a mile away before calling emergency services, but... really? Is it possible she couldn't get a cell signal and didn't want to bother Gabriela?!)

• The entire time that I've been writing this review, I would've sworn that the news infographic spelled Adam's last name "Laing". It does not. Find-and-replace has been undertaken.

• How (and why) is Adam texting Jake? Did he have his phone on him in the reentry capsule, and it managed to survive getting dunked in the ocean, and the aliens didn't find it on him? Or maybe Jake is somehow telepathically wired into their machinery, and was able to mentally interface with the phone network? Which might explain why his text, unlike Jack's message to the Doctor last week, is light on useful information.

• If Jake really believes that it's possible someone has kidnapped Adam, and is holding him inside this building, would his first instinct really be to try to get buzzed in? Bye-bye, element of surprise!

• Likewise, if Jake thinks Adam is being held in this building, shouldn't he be just a little bit suspicious of the two people who show up at exactly the right time with keys to the front door?

• Weirdly, after explicitly asking Jake to "FIND ME", Adam's first words when Jake arrives to rescue him, as requested, are: "Get out." (Is it possible that he knows nothing about Jake's mission? Could it have been the scientists who texted Jake, somehow? That would, after all, explain why Jake doesn't have Adam's number saved in his phone, and seems not to recognize it when it pops up. But that would imply that the scientists wanted Jake for some reason, and they don't seem to care that he exists, beyond feeling the need to shoot at him... at least until he, you know, kills them. I bet they started caring about his existence then. Anyway, if Adam did send the original text, you'd think he might at least send Jake an update once he realizes that Jake will be in danger. "K  NVM  YOU MIGHT DIE" or something.

• How did Jake get to Hong Kong so quickly? The flight from London alone is about 12 hours.

• I'm going to ignore the fact that running does not develop one's pecs, because otherwise this is cute:

  Gabriela: "Ooh. You work out?"
  Ryan: "I do a lot of running."

• Great delivery by Whittaker, and the quote made me LOL:

  Doctor: "Okay. So, with the understanding that was pretty alarming... Don't be overly alarmed."

• But I think this one beats it. As the Doctor runs through her list of inexplicably weird global occurrences:

  Doctor: "There's also a talking cat in Ontario, but I've ruled him out for now."

• Super delivery by Walsh and Gill:

  Graham: "Hey! Hey! Whatever is giving off those weird readings is on the other side of that wall."
  Yaz reverses the device in his hand.
  Graham: "...is on the other side of this door!"
  Yaz: "You're welcome."

• I know they're probably not military-trained, but these alien scientists are terrrrrrrrrrrrible shots. I count 37 shots fired, and not one of them hit their mark.

• I have this impression of Praxeus as being not-terribly-quotable, and yet look at how many lines I'm quoting!

  Doctor: (to Adam) "I hadn't factored you into this... focused too much on that cat."

• Wait wait wait, maybe this is the best line!

  Doctor: (to Ryan) "That's why you smell of dead bird! I thought you'd changed your shower gel."

• Thank you, Graham! I was thinking the same thing!

  Graham: "Doc! Doc, Adam's in a bad way in here. I, I think we made a mistake by disconnecting him from all that gubbins in Hong Kong. ...Or maybe you just wanna stand out here watching birds!"

• Will the Doctor's cure work on seabirds as well as humans? (I think we can assume that the answer is yes, since the virus is half-based on seabird enzymes.)

• I'm not at all clear how microfiltration is helping Suki find a cure for Praxeus. She already knows that it's feeding on the microplastics in the water, so why does she need to filter them out? It feels to me like this is part of her cover story (working for the Crystal Oceans Initiative), not her actual plan. But, gosh, that's an elaborate cover story.

• When Jake says to Graham, "My husband is an astronaut. Do you have any idea how hard it is being married to somebody that impressive?", and the camera racks focus to Graham, does anyone else think that Graham gets a sort of pensive look on his face, as if he's thinking about Grace? If he thinks of her that way, that's quite sweet. (Turns out that lots of people agree, in which case I have to give another visual storytelling thumbs-up to both Walsh and Magnus Stone.)

• Oh my goodness, how has it taken me this long to realize that the doorway to Suki's lab is covered with Hanging Plastic Strips? Hi, Hanging Plastic Strips! I've missed you.

• Another winner from Bradley Walsh:

  Graham: "Hey, Doc, that's not a thought. That's just a random phrase."

• Whittaker's delivery makes this line even more delightful:

  Doctor: "Yaz? How are you doing? 'Cause we've literally got the most exciting rotting bird that I've ever seen."

• My favorite line from this week's batch of reviews, courtesy of Den of Geek's Chris Alcock, regarding Suki's unmasking: "Frankly, after last week’s episode I was half-expecting her to secretly be the Rani. Or another regeneration of the Doctor. Or Frobisher." Amazingly, that possibility had never occurred to me! Ha! Maybe Alcock is actually going to out-Rani me.

• Why is everyone so staunchly against Adam testing the Doctor's cure? Giving how quickly the Praxeus infection is spreading, this unproven treatment is probably literally his only chance at survival.

• Superb delivery by Gill:

  Ryan: "What're you looking like that for?"
  Yaz: (grumpily) "I thought I'd discovered an alien planet on my own."

• Not just a cute line: it's also character growth for Jake (who perhaps decides he was putting Adam on too high a pedestal) as well as helpful (and effortless) foreshadowing!

  Jake: "No idea what any of this means, but is that literally the controls for up, down, left, and right?"
  Doctor: "Yeah."
  Jake: "Adam Lang, your job is so easy!"

• Once the fuel is all jettisoned, how is the ship expected to continue flying? (Is that why it breaks up?)

• I can't believe Gabriela invites herself along on their honeymoon! Ha!

• When is anybody gonna call poor Adam's family to let them know that he did not burn up on re-entry?

• I think this is the first time I've ever seen an episode promo with absolutely zero advance idea of what it was about, not even the title! I'm super excited about Aleppo; Mamluk-era Syria is a cool idea for a setting! And the long-taloned monster looks appropriately terrifying. (Just after Praxeus aired, the episode description finally came out — along with probably the title, though I didn't happen upon that until the next day. Here again, it looks like we've got a story with a wide variety of ill-fitting settings — "Team TARDIS answer cries for help from deep space, 1380 Syria — and Sheffield." — but on the strength of how well Praxeus juggled its disparate plot elements, I shall reserve judgment!

• Along the same lines, I have now seen the title for the next-next episode of Doctor Who, and finally, the title alone excites me! I see that it promises literal Gothic horror creeps! Anything that evokes the Hinchcliffe era is a-okay with me.

Praxeus has loads of plot issues, but ultimately, it's a fast-paced, entertaining mystery, which is cleverly extrapolated from current issues and built around an excellent environmental message, with a couple of great guest characters, and the companions each get a nice role in the plot. Because of all the unanswered questions, it doesn't achieve true greatness, but it's solidly on the high side of average for me.